The objective of the present investigation was to evaluate the effects of taurine and Au nanoparticles on the expression of genes related to embryonic muscle development and on the morphological characteristics of muscles. Fertilised chicken eggs (n = 160) were randomly divided into four groups: without injection (Control) and with injection of Au nanoparticles (NanoAu), taurine (Tau) or Au nanoparticles with taurine (NanoAu + Tau). The experimental solutions were given in ovo, on the third day of incubation, by injecting 0.3 ml of the experimental solution into the air sack. The embryos were evaluated on the 20th day of incubation. The methods included gene expression at the mRNA and protein levels, immunohistochemistry, histology and microscopy. In groups NanoAu, Tau and NanoAu + Tau, the muscle structure and the number of muscle cells were affected. Furthermore, taurine increased fibre diameter, the total number of nuclei, the proportion of proliferating cell nuclear antigen (PCNA)-positive cells and the total cell number. Also, gene expression of basic fibroblast growth factor-2 and PCNA was downregulated. There were no significant interactions between NanoAu and taurine, indicating that NanoAu did not enhance the effects of taurine. It may be concluded that 20 days after injection, NanoAu affected some parameters of muscle development, but the most profound effects were those of taurine.