The issue of fake drugs has been on the increase in Nigeria and is of great concern to the entire populace. Due to the expiration of the patent right of the innovator metformin brand, several generic brands of metformin were introduced into the market and there is fear about the effectiveness of these brands. This study was conducted to authenticate the efficacy or otherwise, of some of the brands of metformin marketed in Southern part of Nigeria. Different brands of metformin hydrochloride tablets were purchased from pharmacies in some states in southern part of Nigeria. The physical properties of the tablets and their packs were assessed. The tablets were evaluated based on official and unofficial tests such as uniformity of weight, hardness, friability, disintegration time, in vitro dissolution and drug content.The results obtained showed that the tablets and their packs had acceptable physical appearance. Tablets from all the brands passed the uniformity of weight test (< 5%), hardness (6.28 ± 0.37 to 36.12 ± 3.24), friability (0.01 to 0.80), disintegration time (2.6 to 8.4 min) and drug content (95.03 to 104.75%). The percentage cumulative drug released from the tablets at 45 min was more than 75% for all the brands.This study showed that all the brands studied passed the various official and unofficial tests and were comparable to the innovator brand. Therefore, any of the brands could be used to substitute for the innovator brand.