Bacteriophages are bacterial viruses and consist ofa single- or double-stranded DNA or RNA protected bya protein capsid. They are able to infect bacteria byinjecting their nucleic acids inside the host. The virusesmultiply and induce lysis of the host cell, or they arestabilized as prophage, either inserted in the bacterialgenome or as independent plasmid molecules. Bacteriophagesrepresent the most numerous micro-organismsfound on earth and play a major role in bacterial evolutionby serving as a genomic reservoir in the environmentand by promoting lateral gene transfer amongbacteria through transduction. They also play a role inbacterial virulence through lysogenic conversion byencoding virulence factors. Bacteriophages, as well astheir recombinant derivatives, are now used in a multitudeof applications in the biotechnology and medicalfields (e.g., as an alternative to antibiotics; tools forscreening libraries of proteins, peptides or antibodies;vectors for protein and DNA vaccines; or as gene therapydelivery vehicles). Although most bacteriophagesdo not represent a threat to human health (unless theyare carrying virulence factors), the use of recombinantviral particles in some instances might raise some biosafetyconcerns by bringing and potentially disseminatingnew genetic traits among bacterial populations. Athorough risk assessment evaluating the properties ofthe manipulated bacteriophages may be required toimplement adequate containment and control measuresto protect human health and the environment. This articledescribes the general characteristics of bacteriophagesthat could pose a risk to human health and theenvironment. Several aspects that should be addressedwhen manipulating them in laboratories are discussed,with illustrations of relevant examples. Finally, basedon the risk assessment conclusion, biosafety recommendations(work practices, safety equipment, and wastemanagement) are proposed.