We study the set of all determinants of adjacency matrices of graphs with a given number of vertices. Using Brendan McKay's data base of small graphs, determinants of graphs with at most $9$ vertices are computed so that the number of non-isomorphic graphs with given vertices whose determinants are all equal to a number is exhibited in a table. Using an idea of M. Newman, it is proved that if $G$ is a graph with $n$ vertices, $m$ edges and $\{d_1,\dots,d_n\}$ is the set of vertex degrees of $G$, then $\gcd(2m,d^2)$ divides the determinant of the adjacency matrix of $G$, where $d=\gcd(d_1,\dots,d_n)$. Possible determinants of adjacency matrices of graphs with exactly two cycles are obtained.

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