The efficiency of composting processes with and without the addition of Californian red worms (Eisenia foetida) was evaluated, using manure of dairy cows to generate organic fertilizer. Several parameters were assessed as physio-chemical indicators of maturity, such as temperature, pH, C/N ratio, phytotoxicity and macro and micronutrients at 25 and 54 ws (mature and stored products, respectively). A linear model was used in the statistical analysis, with four replicates that included as fixed effects, the composting systems and time. At 25 wk, both systems reduced the C/N ratio to values of 15.5 in vermicompost and 17.1 in semi-compost. The content of total N, N-NO3, Ca and some micronutrients also increased. K and Na concentrations were higher in the compost than in the vermicompost. The mean of pH presented differences in the two systems of decomposition. The germination index, using lettuce seeds (Lactuca sativa L.) var. Grandes Lagos in vitro, of the decomposition products increased in week 25, indicating the degree of maturity reached. The effect of storage was greater stability of the products by reducing the C/N ratio to 8.13 for vermicompost and 7.05 for compost, as well as an increase in available N content in the form of N-NO3 in the case of compost and in the content of Ca, Mg, Na, Zn, Mn and Cu in both systems.