A clinical trial was carried out to establish the tolerability, safety and efficacy of Meprasil brand of omeprazole among Nigerians with acid peptic disease using 20mg daily or 20mg bid of Meprasil. Forty patients were enrolled for the study and were asked to rate their abdominal pains pre-commencement of therapy using a scale of mild, moderate or severe. Serum alanine transaminase (ALT), urinalysis, electrolytes, creatinine and urea were carried out before and after treatment. Patients were then evaluated on days 0, 1, 3, 7, 14, and 28, thereafter monthly for 4 months for relief of symptoms and adverse drugs effect. Only 32 patients completed the study, 17 (Group I) and 15 (Group II). Symptoms included abdominal pain (100%), vomiting 9.4%, haematemesis 3.1%, anorexia 25.0% and diarrhea 15.6%. Pain was rated as moderate in most patients (46.4%), mild in 21.4% and severe in 32.1%. Alanine transaminase (ALT) 27.8+ 11.7 IU/L, Sodium 137+ 4.3 mmol/L, Potassium 3.8+0.46mmol/L, Chloride 103.1+4.0mmol/L, Bicarbonate 22.4+1.8mmol/L, Urea 21.9+5.1mg/dl, creatinine 1.1+0.23mg/dl. No patient had glycosuria prior to enrolment while 2 out of 31 (6.5%) had a mild proteinuria. Ranked adverse drug reaction included diarrhea (21.9%), headache (21.9%), flatulence (15.6%), nausea (12.5%), constipation (9.4%), pruritus (9.4%), skin rashes (6.3%), dizziness (3.1%) and abdominal pain (3.1%). Intensity of painand adverse events reported during follow up between the two doses of Meprasil showed no significant difference. The biochemical parameters before and after treatment among both treatment groups were similar. In conclusion, this study has shown that Meprasil taken as 20mg or 20mg twice daily, is safe, efficacious and well tolerated in amelioration of pain of acid peptic disorder among Nigerian patients. (Afr. J. Biomed. Res. 10: 229 – 234) Key words : - Meprasil, efficacy, tolerability, Dyspepsia, Nigerians