diff --git a/rules.go b/rules.go
index c171783..08f909f 100644
--- a/rules.go
+++ b/rules.go
@@ -19,6 +19,7 @@ type Rules struct {
 	MustMatch            *regexp.Regexp
 	MinLength, MaxLength int
 	MinLetters           int
+	MinLower, MinUpper   int
 	MinNumeric           int
 	MinSymbols           int
 	AllowWhitespace      bool
@@ -49,10 +50,16 @@ func (r Rules) Errors(toValidate string) ErrorList {
 		errs = append(errs, FieldError{r.FieldName, errors.New(r.lengthErr())})
 	}
 
-	chars, numeric, symbols, whitespace := tallyCharacters(toValidate)
-	if chars < r.MinLetters {
+	upper, lower, numeric, symbols, whitespace := tallyCharacters(toValidate)
+	if upper+lower < r.MinLetters {
 		errs = append(errs, FieldError{r.FieldName, errors.New(r.charErr())})
 	}
+	if upper < r.MinUpper {
+		errs = append(errs, FieldError{r.FieldName, errors.New(r.upperErr())})
+	}
+	if upper < r.MinLower {
+		errs = append(errs, FieldError{r.FieldName, errors.New(r.lowerErr())})
+	}
 	if numeric < r.MinNumeric {
 		errs = append(errs, FieldError{r.FieldName, errors.New(r.numericErr())})
 	}
@@ -89,6 +96,12 @@ func (r Rules) Rules() []string {
 	if e := r.charErr(); len(e) > 0 {
 		rules = append(rules, e)
 	}
+	if e := r.upperErr(); len(e) > 0 {
+		rules = append(rules, e)
+	}
+	if e := r.lowerErr(); len(e) > 0 {
+		rules = append(rules, e)
+	}
 	if e := r.numericErr(); len(e) > 0 {
 		rules = append(rules, e)
 	}
@@ -119,6 +132,20 @@ func (r Rules) charErr() (err string) {
 	return err
 }
 
+func (r Rules) upperErr() (err string) {
+	if r.MinUpper > 0 {
+		err = fmt.Sprintf("Must contain at least %d uppercase letters", r.MinUpper)
+	}
+	return err
+}
+
+func (r Rules) lowerErr() (err string) {
+	if r.MinLower > 0 {
+		err = fmt.Sprintf("Must contain at least %d lowercase letters", r.MinLower)
+	}
+	return err
+}
+
 func (r Rules) numericErr() (err string) {
 	if r.MinNumeric > 0 {
 		err = fmt.Sprintf("Must contain at least %d numbers", r.MinNumeric)
@@ -133,11 +160,15 @@ func (r Rules) symbolErr() (err string) {
 	return err
 }
 
-func tallyCharacters(s string) (chars, numeric, symbols, whitespace int) {
+func tallyCharacters(s string) (upper, lower, numeric, symbols, whitespace int) {
 	for _, c := range s {
 		switch {
 		case unicode.IsLetter(c):
-			chars++
+			if unicode.IsUpper(c) {
+				upper++
+			} else {
+				lower++
+			}
 		case unicode.IsDigit(c):
 			numeric++
 		case unicode.IsSpace(c):
@@ -147,5 +178,5 @@ func tallyCharacters(s string) (chars, numeric, symbols, whitespace int) {
 		}
 	}
 
-	return chars, numeric, symbols, whitespace
+	return upper, lower, numeric, symbols, whitespace
 }
diff --git a/rules_test.go b/rules_test.go
index 15ce0b8..07b2e4a 100644
--- a/rules_test.go
+++ b/rules_test.go
@@ -48,6 +48,16 @@ func TestRules_Errors(t *testing.T) {
 			"13345",
 			"email: Must contain at least 5 letters",
 		},
+		{
+			Rules{FieldName: "email", MinUpper: 5},
+			"hi",
+			"email: Must contain at least 5 uppercase letters",
+		},
+		{
+			Rules{FieldName: "email", MinLower: 5},
+			"hi",
+			"email: Must contain at least 5 lowercase letters",
+		},
 		{
 			Rules{FieldName: "email", MinSymbols: 5},
 			"hi",
@@ -90,8 +100,10 @@ func TestRules_Rules(t *testing.T) {
 		MinLength:       1,
 		MaxLength:       2,
 		MinLetters:      3,
-		MinNumeric:      4,
-		MinSymbols:      5,
+		MinUpper:        4,
+		MinLower:        5,
+		MinNumeric:      6,
+		MinSymbols:      7,
 		AllowWhitespace: false,
 	}
 
@@ -101,8 +113,10 @@ func TestRules_Rules(t *testing.T) {
 		"Must adhere to this regexp",
 		"Must be between 1 and 2 characters",
 		"Must contain at least 3 letters",
-		"Must contain at least 4 numbers",
-		"Must contain at least 5 symbols",
+		"Must contain at least 4 uppercase letters",
+		"Must contain at least 5 lowercase letters",
+		"Must contain at least 6 numbers",
+		"Must contain at least 7 symbols",
 	}
 
 	for i, toFind := range mustFind {
@@ -128,9 +142,12 @@ func TestRules_IsValid(t *testing.T) {
 func TestTallyCharacters(t *testing.T) {
 	t.Parallel()
 
-	c, n, s, w := tallyCharacters("123abcDEF@#$%^*   ")
-	if c != 6 {
-		t.Error("Number of chars:", c)
+	u, l, n, s, w := tallyCharacters("123abcDEF@#$%^*   ")
+	if u != 3 {
+		t.Error("Number of upper:", u)
+	}
+	if l != 3 {
+		t.Error("Number of lower:", l)
 	}
 	if n != 3 {
 		t.Error("Number of numerics:", n)