Gaucher disease is an autosomal recessive disorder caused by mutations in the lysosomal beta-glucocerebrosidase (GBA) gene. Gaucher disease is a very heterogeneous entity due to the large number of different mutations existing in the GBA gene, resulting in a defective protein whose impaired activity is the cause of the disease. We present a mutation analysis of the GBA gene in 51 unrelated Spanish Gaucher disease patients together with clinical findings. Two common mutations, c.1226A>G (N370S) and c.1448T>C (L444P), were determined by restriction enzyme digestion after PCR amplification of genomic DNA. The remaining alleles were screened by amplifying the entire GBA gene followed by nested PCR and SSCP analysis under four different conditions. The c.1226A>G (N370S) and c.1448T>C (L444P) mutations were common, accounting for 56 alleles (55%) and 16 alleles (15%), respectively. In addition, 25 different mutations were found, 11 of which are described here for the first time: c.(-203)A>G, c.160G>A (V15M), c.256C>T (R47X), c.445-2a>g (IVS4-2a>g), c.485T>C (M123T), c.914C>T (P266L), c.953delT, c.1124T>C (L336P), c.1207A>C (S364R), c.1214delG,C, and c.1510delT,C,T (465delSer). Two mutations, S364R and P266L, were associated with neuronopathic forms of Gaucher disease: S364R mutation in heterozygosity with the L444P mutation and the P266L mutation in a homozygous state. Two type 1 patients were found to be carriers of two mutations in the same allele (genotypes [N370S] + [E326K + N188S] and [N370S] + [IVS4-2a>g+c.(-203)A>G]). This study allowed us to identify 100% of mutant alleles, and therefore we conclude that the method used to screen for mutations in the GBA gene is very reliable and there is a broad spectrum of mutations in the GBA gene in the Spanish population.