This study used the 1998/1999 Ghana Living Standards Survey (GLSS 4), a new nationally, representative survey carried out by the Ghana Statistical Service (GSS) and applied the decomposition to empirically analyse the phenomenon of gender gap in earnings in the informal sector labour market. The findings suggest the existence of discrimination in gender earnings in the Ghanaian informal sector labour market and that females in the Ghanaian informal sector labour market are on average and ceteris paribus more skilful by 36%. However, males having sample average female characteristics earn on average and ceteris paribus 87% more in log monthly wages than their female counterparts.